The major goal of this proposal is to identify melanoma-associated antigens that are candidate vaccines for active immunotherapy of these patients. The antigens will be defined by patients' B cells. Specifically, immunogenic antigens will be identified by combinatorial antibody (Fab) libraries derived from patients' lymphocytes and expressed on the surface of filamentous phages. This approach has numerous potential advantages over conventional approaches using monoclonal antibodies (mAb) derived from hybridomas or Epstein Barr Virus (EBV)-transformed B cells. Preferential expression of combinatorial Fab-selected structures by melanoma cells as compared to normal tissues would suggest their usefulness as modulators of patients' humoral immunity to their tumors. In light of previous demonstrations of both helper and cytolytic T-cell (CTL) epitopes on antigens originally defined by B cells, selected antigens also may induce cellular immunity in patients. The specific aims are to; 1) express combinatorial Fab libraries derived from melanoma patients' B cells on the surface of filamentous phages (M13) using the pComb-3H vector, and select those Fab binding to protein antigens preferentially expressed by melanoma cells as compared to normal cells; 2) characterize, clone and express protein antigens defined by selected combinatorial Fab; and 3) determine the reactivities of selected antigens with patients' T cells. Selected antigens may be used in future studies for active immunotherapy of melanoma patients.